The present invention relates to electrical connectors and, more particularly, to electrical connectors having at least one contact which is removably retained within a connector housing by means capable of centering and stably retaining the contact.
In the electrical connector art, it is known to utilize a stamped sheet metal contact within an insulated housing. An example of such a sheet metal contact is shown in U.S. Pat. No. 2,689,337 by H. H. Burtt et al. The contact shown is stamped and rolled from a metal sheet to include two leaf springs which engage an internal shoulder formed in a bore passing through the insulated housing and a second stop tab which engages an outer shoulder formed by the bore at the surface of the housing.
In U.S. Pat. No. 3,178,673 by J. H. Krehbiel, a sheet metal contact is shown which is used for a so-called 0.093 series electrical connector. Here, the contact is retained within a cylindrical bore in an insulated housing by leaf springs which engage a shoulder formed in the bore and wing flanges which engage a second shoulder on the opposite side of the bore from the first-mentioned shoulder. The contact also has two flared skirts formed by flaring the edge of a longitudinal slot in the contact, and a protruding rib which engage the parallel surfaces of the bore to provide contact centering. In this arrangement, as the contact is inserted into the bore, there must be a clearance between the distance from the stop provided by the wing flanges and the leaf springs and the distance from the first and second shoulders in order for the leaf springs to snap outwardly for retention of the contact within the housing bore. Once installed, the contact is free to rotate about its longitudinal axis and to move along its longitudinal axis within the clearance required to permit the leaf springs to function properly. This rotation and forward to backward motion decreases the stability of the contact. The contact is also free to rock from side to side about a fulcrum formed by the skirts as they contact the bore due to the clearance mentioned above and due to the uneven distribution of the two flared skirts and protruding rib within the cylindrical bore.
A second electrical contact by Krehbiel is shown in U.S. Pat. No. 3,465,279 which is utilized within a so-called 0.062 series electrical connector. This contact is latched by the interaction of leaf springs on one side of a cylindrical bore and two protruding flange portions flared from a slot edge and a square flange on the other side. The centering action is obtained by a longitudinal rib. This contact is again prone to forward and backward motion due to the stop provided by the square flange, in spite of the tapering arrangement of the two flared flanges which engage a square shoulder in the bore. Rocking due to the close proximity of the two flared flanges also remains a problem.
In U.S. Pat. No. 3,790,923 by I. Mathe a similar electrical connector to the connectors discussed above is shown having three key-like embossments equally distributed about the periphery of the contact. These embossments form square shoulders which cooperate with an internal square shoulder formed within a cylindrical bore passing through the connector housing. This same bore has a second square shoulder which is engaged by a latch spring and two flanges flared from the lateral edge of a longitudinal slot. As before, this contact has a tendency to move forward and backward within the housing due to the clearance required to free the latch springs during the insertion of the contact into the housing. Contact centering is provided and rocking is prevented by a large diameter resilient collar which has a slight press fit with the enlarged portion of the housing bore.
A final electrical connector which should be considered as background of the invention is shown in U.S. Pat. No. 3,783,440 by S. Karube et al. In this electrical connector, the contact is retained within the housing bore by leaf springs which engage a square shoulder, while it is retained against motion in the opposite direction by a tapered bellmouth contact portion which engages a tapered surface within the housing bore having the same taper angle. A resilient hook is also provided to retain the contact against motion in the opposite direction. While the arrangement of two identical tapers provides adequate centering, it should be noted that the area required by each contact is somewhat larger than the prior art because of the bellmouth configuration. Further, the insertion force required to insert the two equal tapers against each other until the leaf springs are clear of the square shoulder is substantial. In FIG. 8 of the Karube reference three cut-up protrusions are shown which may be used in place of the resilient bellmouth portion. These cut-up protrusions are said to provide spring resilience when inserting the contact into the housing. In practice, however, these protrusions have little, if any, resilience. It is necessary to shear the cut-up protrusions into the sheet metal contact prior to rolling the contact into the desired shape. The cone configuration of the bellmouth contact with the three cut-up protrusions shown is difficult to manufacture. Further, the flat outer surface of the cut-up protrusions forms a three-surface contact area with the tapered housing bore which does not readily yield when configured as shown and thus requires a clearance between the contact surface and the ends of the leaf springs. Therefore, the undesirable forward to backward motion of the contact within the housing is still possible.